Aircraft fitting



Aug. 7, 1923. 1463,888

C. W. HALL AIRCRAFT FITTING Filed April 9, 1921 4 Sheets-Sheet l 11 s f215 c? E0 BVM.

A TTU/MIE V Aug. 7, w23. Messs C. W, HALL AIRCRAFT FITTING Filed April9, 1921 4 Sheets-Sheet 2 TTU/ME Y Aug. 7, 1923. 1,463,888

v C. W. HALL AIRCRAFT FITTING Filed April 9, 1921 4 Sheets-Sheet 4 @Newmi /m till Patented ug, 7, l923..

CHARLES "WARD HALL, 0F LARCHMONT, NEW YDRK.

AIRCRAFT FITTING.

Application tiled April 9, 1921.

To all whom t may concern.'

Be it known that l, CHARLES WARD HALL, a citizen ofthe United States,and a resident of Larchmont, in the county of Westchester and State ofNew York, have invented certain new and useful Improvements in AircraftFittings, of which the following is a s ecication.

y present invention relates to aircraft fittings, and, morespecifically, to a joint fitting by which to join together a pluralityof parts or members having oblique, or at least non-parallel, lines ofaction; and the object of my improvements is to provide a form ofjointure which with a minimum amount and Weight of metal not only willefficiently transmit the direct stresses of tension or compressiomorboth, through an oblique angle vbut also affords a means forcontrolling, and thereby substantially eliminating or distributing asdesired, the indirect stresses, such as those of bending and torsion. l

To this end, the invention comprises, as its principal feature, aball-head bolt and, in combination therewith, a metal plate which aroundthe opening through which the bolt passes is curvilinearly cupped to fitthe curved inner surface of the bolt head and has leading therefrom, atan acute angle to the axis of the cup and bolt, one or more integralstraps or arms, curved at the rim in substantial conformity therewithand acting thereon through a considerable arc,

each of which serves either as an anchorage for a diagonal stay wire orfor the support of a corresponding tension compression brace member. Theradius of curvature of the bolt head and inner surface of the cuppedplate should be approximately equal to the diameter of the bolt, tosecure the best functional relationship between these parts, and eachanchorage arm is preferably cut away centrally, through a portion of itslength, so as to provide two forks or branches more or less separatedone from the other Lat the rim of the cup. This division of an arm maybe omitted whenever its angular lead approaches a right angle to theaxis of the cup, but becomes more and more important, and calls for agreater and eter degree of se eration of the two forks, the more acute te angle of lead. For example, where the lead of the arm is at an an leof forty-five degrees, the central or amel lines of its forks should beapproxiof the socket.

Serial N0. 459,889.

mately ninety-five degrees apart at the rim of the cup, and as the' leadangle approaches z^ro the two forks should lead ed as nearly aspracticable from diametrically opposite sides of the cup. lin case thelead angle is less than'thirty degrees, however, I prefer to form theforked arm by making two separate arms and bringing together landoverlapping their outer ends, since otherwise it is diiiicult orimpossible to shape up the plate without rupturing the forks at the rimof the cup. By a 'joint thus formed the direct stresses of tension andcompression will be transmitted without subjectin the bolt to bendingstress, thereby su stantially doubling its effective strength, andwithout torsion in the part or member to which the plate is bolted.

A second feature is provided by a special taperlng terminal extension,specifically shown as a separable cone-shaped socket having differentdegrees of taper on its outer and inner surfaces to thereby give thewalls their greatest vthickness adjacent the tip and open base ofthecone, with which to join a tubular strut' concentrically with diagonalstay wires. The socket, with the end of the strut abutting against thebase of the cone and held centered thereon by a depending annular skirt,is in Vturn held by the stay wires in butt engagement with the head ofthe bolt through a ball and socket connection, the ball being formedeither on the outer surface of thebolt head or on the tip lt has beenfound that such socket with properly tapered walls fails in tension,whereas a socket with walls of equal thickness fails through shear, andconsequently, when made of duralumin for example, has a unit strengthfully twice that of the ordinary socket.

Still another feature of the invention consists, where for instancestruts and diagonals such as staywires and braces are to be joined to alattice girder, in a single or double web plate, of substantiallyY or Xshape, which is inserted in and as a part of the lattice web and'to thecenter of which the cupped plate is or may be bolted. This plate mayalso have at top or bottom, to project beyond the chords of the girder,one or more vend extensions or ears for the support of a strutor towhich yto anchor an additional stay wire or wires. The outwardlytapering sides or side extensions provided at either or both of its endsby a web plate of the shape indicated will, when united in the chordslend to end with the diagonal web members adjoining on either side giveto the web a continuity which will enable it to transmit the webstresses uniformly, thereby keeping ata minimum the indirect stresses inthe panels of the girder adjoining the two sides of the plate whichstresses, when the girder is subjected to column action, otherwise mightbe fully as great as the direct stresses and have in the past causeddisastrous failures. In the joint thus formed the converging lines ofaction of all of the non-parallel members which are to be joined therebyare centered at or near the `gravity axis ofthe girder as desired.

The invention is shown, by way of illustration and not of limitation, inthe accompanying drawings, in whichl Figure 1 is a view' showing, inperspective a portion of a wing spar of an airplane, adjacent a driftpanel point, and joint fittings, for joining thereto a driftstrut, adrift wire and its counter, and other wires, embodying the severalfeatures of my invention; Fig- 2, a central vertical section through thejoint of Fig. 1; Fig. 3, a face or plan view of the blank from which thecupped plate member of the joint is shaped up; Fig. 4, a view showing,in elevation, the portion of a Wing spar adjoining a lift-drift paneloint and the joint ttings for the lift and (Pirift struts, lift anddrift wire and their counters, and other stay wires; Figs. 5 4and 6,central vertical and horizontal sections,

respectively, through the joint of Fig 4; Fig. 7, a face view of theblank for each part of the double cuppe'd plate of the joint; igs. 8 and9, views showing diagrammatically, in broken perspective and in planrespectively and on somewhat differentk scales, a ,tetrahedral frame ofone-half of an airplane wing embodying certain` but not all of thefeaturesof myinvention;Y

Fig. 10, a detail of the tetrahedralframe of Figs.- 8 and 9 showing, inperspective, a

. typical joint fitting; Fig. 11, a central section through the joint ofFig. 10; and Fig. 12, another detail of the tetrahedral frame showing,in perspective, one of the diagonal or brace members and the jointfittings both for its upper and lower ends.

Similar reference characters designate like arts throughout the severalfigures of the rawings.

Referring first to Figs. v1-3 of the drawings,the spar 1 is of latticetruss construction, with mul-titubular chords and a double web formed oftubing and spaced apart by the middle tube of the chords. The double webmember 2, consisting of two inverted- Y plates shaped to contact midwayof their length and to stand properly spaced apart at top and bottom,isl framed into the spar with the ends of the plates straddling themiddle tube of the chords; and, with the downwardly and outwardlyinclined sides or side extensions 3 formed by their bifurcated lowerends thinned and set to overlap end to end the adjacent tubulardiagonals, give to the web the desired structural and functionalcontinuity. One of the web plates is provided at its upper end with anear 4 and on one fork of its lower end with an ear 5, which ears serveas anchorages for control leads and are bent over laterally to bringthem into alignment therewith. To the center of this double web plates,drilled at 7 for the purpose, there is bolted, by the ball-head bolt 8,the spherically cupped plate 9 which has drilled in the bottom or axisof the cup (preferably, to prevent distortion, after the blank has beenshaped up) a hole 10 through which the bolt passes. The radius ofcurvature of the bolt head and of the cup is, as shown, equal to thediameter of the bolt. The cupped plate has two oppositely disposed arms11 and 12 which lead therefrom at an angle of approximately forty-five'degrees to the axis of the cupand are cut away at 13 and 14,respectively, to divide each into two J.forks separated about ninetydegrees one from the other at the rim of the cup. The outer end of thearm 11 is drilled at 15 to receive the bushing 16, and a drift wire 17is anchored thereto by a clevis 18 and clevispin 19; or, if founddesirable, a clevis can be frmed integral with the arm by making the armof sufficient length and doubling it back and nesting its cupped outerend in the cup of the plate. The arm 12 is also drilled at 20, orotherwise shaped, for the anchorage kthereto of the counter drift wire.The drift strut 23 is joined to the spar concentrically with the driftwire Vand its counter,.by the cone-shaped socket 24, formed with astraight taper of thirty to forty-five degrees on its outer surface andwith its inner surface concavely tapered to give to the walls theirgreatest thicknessnat the base of the cone, which is provided at itsbase with an annular skirt 25 to receive and hold in position the end ofthe strut and in connections. The two plates of the double web member2", shaped to Straddle at their ends two of the four tubes of the chordsof the spar 1, are here of a more or less X- shape providing both upperand lower taperate ear 6a.

rae

ing side extensions 3a, and both plates are extended beyond the 'chordtubes at their lower ends (for the upper wing spar shown) to providelateral ears 5a and an intermedi- The double cupped plate 9, consistingof two similar plates nested together, is bolted to the center of theweb plates by the ball-head bolt 8*; and of the four arlns with whichthis cupped plate is provided, the oppositely disposed forked arms'llaand 12l serve, as before, for the anchorage of a drift wire and itscounter, while a third arm 21, extending in a plane at substantiallyright angles to the plane of the two forked arms and having a lead angleof about sixty degrees to the axis of the cup, serves as an anchoragefor an incidence wire,

and the fourth arm 22a, leading from their rim of the cupped plate at anacute angle to and for a portion of its length integral with the arm 12,provides an anchorage for a stay wire from the body of the airplane.These two additional arms are not cut away and forked because of thehigh lead angle of one and the low stressesV to which the otherisvsubjected. The plates shouldbe drilled, at the bottom of the cup forthe bolt ,and at the ends of the arms for the clevis-pins, after theblanks have been shaped up and the two plates nested together. A driftstrut 23 is here joined to the spar in the manner, and by means of thesame cone-shaped socket 24, heretofore described. For the attachment ofthe lift strut 27, the strut has secured to its end a cap 28 withparallel projecting lugs 29 which fit between and are pivoted to theintermediate ears 6 of the web plates by a clevis-pin 30. The lateralears 5a of the double web plate, drilled to receive clevis- .pins (onone side with the addition of a bushing), provide anchorages for a liftwire and its counter. lt will be observed that here, as in the jointpreviously described, the lines of action of all the different jointmembers are brought at dilerent angles and from diiterent planes to acommon point substantially at the gravity axis of the spar.

The tetrahedral wing frame illustrated in the remaining figures of thedrawings comprises upper longitudinals and transverse connecting members31 and 32, similar lower longitudinals and transverse connecting members33 and 34, and a plurality of regularly disposed diagonal braces 35 eachof which is joined at one end, with two others,

to an upper panel lpoint and at the other end, with two other butdifferent braces, to a lower panel point. As shown, each of thelongitudinale is a spar of four tubes and both the transverse connectingmembers and the diagonal braces are also tubular. The

joint ttings at each panel point consist of the )(-shaped web plate 2b,framed horizontally between the upper and lower tubes of f thelongitudinal spar and -extended at their ends to provide the' four armsab and 5b, and the cupped plate 9b which is bolted centrally to the webplate, by al ball-head bolt 8b, and has three arms extending therefromin planes at equal angles to each other. rllhe shaped ends 32b of fourtransverse connecting members'are telescopically united to the four armsof the vweb plate, and the similarly shaped ends 35D of three diagonalbraces are in like manner united to the three arms oit' the cuppedplate.

lt will of course be understood, from the above illustrations, that theseveral features of my invention may either be combined to-4 gether in asingle joint fitting or may be used separately as desired, and that eachmay be modified in its structural details,

within the scope of the appended claims,

without departing from the spirit or sacrificing the advantagesthereor".

What 1 claim as new, and desire to secure by Letters Patent, is I 1. Ajoint fitting which comprises a curvilinearly cupped metallic platehaving in the bottom of the cup an opening through which to pass a boltand leading therefrom one or more integral arms curved at they rim'insubstantial conformity therewith.

2. A joint fitting which comprises a curvilinearly cupped metallic platehaving in the bottom of the cup an opening through which to pass a boltand leading out therefrom a lateral arm integral with the rim anddivided thereat into two spaced forks.

3. A joint fitting which comprises a cupped metallic plate having in thebottom of the cup an opening through which to pass a bolt and integralwith 4its rim an arm leading therefrom at an obliquejangle to the axisof the cup and divided into two forks separated one from the other atthe rim of the cup to a degree dependent upon and varyingl inverselywith the angle ot lead et the arm.

4. A joint fitting which comprises a member with hollow terminal havingwalls gradually contracting in diameter and increasing in thiclmess ineach axial section as they approach the outer end.

5. A joint fitting which comprises a member with hollow socket terminalhaving. walls .with contracting inner and outer surlos faces one a.dome-shaped and the other a substantially conical surface.l

6. A joint htting which comprises a coneshaped socket havin wallstapering in thickness between a skirt enclosed open base and a closedtip.

7. A joint fitting which comprises a coneshaped socket having wallstapering in thickness between a skirt enclosed open base and a closedtip the youter end surface of which is herically curved.

8. A joint htting which. comprises a metallic plate which is adapted toform a part of the web of a' girder and has tapering side extensions atone at least of its ends.

9. A joint fitting which comprises, as elements thereof, a bolt having ahead with curved inner surface and a metallic plate curvilinearly cuppedto fit the head of the bolt and having in the bottom of the cup anopening through which to pass the bolt a d integral with the rim one ormore arms leading therefrom and adapted to distribute the stress of theload transmitted thereby through a considerable arc of the rim.

10. A joint fitting which comprises, as elements thereof, a bolt havinga head with inner surface spherica-lly curved and a metallic platespherically cupped to tit the head of the bolt and having in the vbottomof the'cup an opening through which to pass the bolt and one or morelateral extensions leading therefrom and curvilinearly connected withthe rim of the cup through a considerable are thereof.

11. A joint fitting which comprises, as elements thereof, a bolt havinga head with inner surface spherically curved, and a spherically cuppedmetallic plate having in the bottom of the cup an opening through whichto pass the bolt and integral with the rim an arm leading therefrom atan oblique angle to the axis of the cup and cut away through a portionof its length to provide two forks separated one from the other at therim ofthe cup. Y

12. A joint fitting which comprises, as elements thereof, a bolt havinga head with inner surface curved on a radius approximately equal to thediameter of the bolt, a metallic plate which is cupped to fit the headofthe bolt and has in the bottom of the cup an opening through which to`pass the 4bolt and integral with the rim an arm f leading therefrom atan acute angle to the axis of the cup and divided through a portion ofits length to provide two forks separated one from the other at the rimof the cup to a degree dependent upon the angle of lead of the arm.

13. A concentric joint fittin which comprises, as elements thereof, aolt having a .heed with curved inner surface, a cupped metallic plateadapted to receive the bolt and having integral anchorage arms leadingtherefrom at an oblique angle to the axis of the cup, and a taperedsocket havin a curved tip adapted to make and be hel in butt contactwith the complementarily curved outer surface of the bolt head.

14. A concentric joint fitting which comprises, as elements thereof, abolt having ay head with inner' surface spherically curved, aspherically cupped plate adapted to receive the lbolt and having anintegral anchorage arm leading therefrom at an oblique angle to the axisof the cup, and a coneshaped socket with walls gradually tapering inthickness between base and tip and adapted at the tip to lit and be heldin ball and socket engagement with the head of the bolt.

15. A concentric joint fitting which comprises, as elements thereof, aplate adapted to form a part of the web of a girder and havingtaperingly inclined side extensions at one at least of its ends and acentral opening through which to pass a bolt, a cupped plate having atthe bottom of the cup an opening through which to pass a bolt andintegral with the rim one or more arms leading therefrom at an obliqueangle to the axis of the cup, and a bolt having a head with curved innersurface by which to secure the two plates together.

16. A concentric joint fitting which comprises, `as elements thereof, aweb vplate having taperingly inclined side extensions at one at least ofits ends and a centrally located opening through which to pass a bolt, acupped plate having at the bottom of the cup an opening through which topass a bolt and integral with the rim anchorage arms leading outwardlytherefrom at an oblique angle to the axis of thecup, a bolt having ahead with curved inner surface by which to secure the two platestogether, and a tapered socket having walls tapering in thickness frombase to tip and adapted at the tip to be held by a ball and socketengagement in butt contact with the head of the bolt.

CHARLES WARD HALL.

